As each rivet is then in double shear, and twice the previous
strength, the pitch may be considerably increased, but this cannot
be taken advantage of, except perhaps in the thickest plates, or
staunchness would be affected.
A Double-riveted Butt Joint with two Coverplates
is shewn in Fig. 363, designed to use the full strength of rivets.
Of course the links, will be twice the width of a lap joint,
.•./' = 4 (
and diagonal centres = 2 (1-09)+^= 2*1
The butt strap might be \t in thickness, but is safer at f /. It
might have to be thicker and should always be examined separately,
as one plate equal to the two straps put together. The overlap
may also have to be increased as at 2d.
The Treble-riveted Butt Joint at Fig. 364 is taken from
Examining as a butt joint, width of one link= '83:8 x 2 = 1*67 6"
and /'c=5 (1-676) + 1*28 » 9*66"
marine practice. Using the general formula (page 407), (J>
= *%3&" j but as 5 links must pass at the pitch line :
Examining as a lap joint, width of one link = '838"
and /' = 5